Browsing by Author "Navarro, Gonzalo"

Now showing items 1-20 of 25

    • A succinct data structure for self-indexing ternary relations 

      Álvarez García, Sandra; Bernardo, Guillermo de; Brisaboa, Nieves R.; Navarro, Gonzalo (Elsevier BV, 2016-10-27)
      [Abstract] The representation of binary relations has been intensively studied and many different theoretical and practical representations have been proposed to answer the usual queries in multiple domains. However, ternary ...

    • Aggregated 2D range queries on clustered points 

      Bernardo, Guillermo de; Konow, Bernardo; Navarro, Gonzalo; Brisaboa, Nieves R.; Seco, Diego (Elsevier Ltd, 2016-09)
      [Abstract] Efficient processing of aggregated range queries on two-dimensional grids is a common requirement in information retrieval and data mining systems, for example in Geographic Information Systems and OLAP cubes. ...

    • An index for moving objects with constant-time access to their compressed trajectories 

      Brisaboa, Nieves R.; Gagie, Travis; Gómez-Brandón, Adrián; Navarro, Gonzalo; Paramá, José R. (Taylor & Francis, 2021)
      [Abstract]: As the number of vehicles and devices equipped with GPS technology has grown explosively, an urgent need has arisen for time- and space-efficient data structures to represent their trajectories. The most commonly ...

    • Clustering-based compression for raster time series 

      Muñoz, Martita; Fuentes Sepúlveda, José; Hernández, Cecilia; Navarro, Gonzalo; Seco, Diego; Silva-Coira, Fernando (Oxford University Press, 2024-09-29)
      [Abstract]: A raster time series is a sequence of independent rasters arranged chronologically covering the same geographical area. These are commonly used to depict the temporal evolution of represented variables. The ...

    • Compact representations of spatial hierarchical structures with support for topological queries 

      Fuentes Sepúlveda, José; Gatica, Diego; Navarro, Gonzalo; Rodríguez, M. Andrea; Seco, Diego (Elsevier Inc., 2023-06)
      [Abstract]: Among different spatial data models, the topological model for spatial regions explicitly represents common boundaries. This model pursues the efficiency of topology-related queries and the elimination of data ...

    • Efficient and Compact Representations of Some Non-canonical Prefix-Free Codes 

      Fariña, Antonio; Gagie, Travis; Manzini, Giovanni; Navarro, Gonzalo; Ordóñez, Alberto (Springer, 2016-09-21)
      [Abstract] For many kinds of prefix-free codes there are efficient and compact alternatives to the traditional tree-based representation. Since these put the codes into canonical form, however, they can only be used when ...

    • Efficient Representation of Multidimensional Data over Hierarchical Domains 

      Brisaboa, Nieves R.; Cerdeira-Pena, Ana; López López, Narciso; Navarro, Gonzalo; Penabad, Miguel R.; Silva-Coira, Fernando (Springer, 2016-09-21)
      [Abstract] We consider the problem of representing multidimensional data where the domain of each dimension is organized hierarchically, and the queries require summary information at a different node in the hierarchy of ...

    • Exploiting Computation-Friendly Graph Compression Methods for Adjacency-Matrix Multiplication 

      Francisco, Alexandre P.; Gagie, Travis; Ladra, Susana; Navarro, Gonzalo (IEEE Computer Society, 2018-03)
      [Abstract] Computing the product of the (binary) adjacency matrix of a large graph with a real-valued vector is an important operation that lies at the heart of various graph analysis tasks, such as computing PageRank. In ...

    • Extending general compact querieable representations to GIS applications 

      Brisaboa, Nieves R.; Cerdeira-Pena, Ana; Bernardo, Guillermo de; Navarro, Gonzalo; Pedreira, Óscar (Elsevier, 2020-01)
      [Abstract]: The raster model is commonly used for the representation of images in many domains, and is especially useful in Geographic Information Systems (GIS) to store information about continuous variables of the space ...

    • Faster compressed quadtrees 

      Bernardo, Guillermo de; Gagie, Travis; Ladra, Susana; Navarro, Gonzalo; Seco, Diego (Elsevier B.V., 2023-02)
      [Abstract]: Real-world point sets tend to be clustered, so using a machine word for each point is wasteful. In this paper we first show how a compact representation of quadtrees using O(1) bits per node can break this bound ...

    • GraCT: A Grammar Based Compressed Representation of Trajectories 

      Brisaboa, Nieves R.; Gómez-Brandón, Adrián; Navarro, Gonzalo; Paramá, José R. (Springer, 2016-09-21)
      [Abstract] We present a compressed data structure to store free trajectories of moving objects (ships over the sea, for example) allowing spatio-temporal queries. Our method, GraCT, uses a k2k2 -tree to store the absolute ...

    • GraCT: A Grammar-based Compressed Index for Trajectory Data 

      Brisaboa, Nieves R.; Gómez-Brandón, Adrián; Navarro, Gonzalo; Paramá, José R. (Elsevier Ltd, 2019)
      [Abstract]: We introduce a compressed data structure for the storage of free trajectories of moving objects that efficiently supports various spatio-temporal queries. Our structure, dubbed GraCT, stores the absolute positions ...

    • Grammar compressed sequences with rank/select support 

      Ordóñez, Alberto; Navarro, Gonzalo; Brisaboa, Nieves R. (Elsevier BV, 2016-10-14)
      [Abstract] Sequence representations supporting not only direct access to their symbols, but also rank/select operations, are a fundamental building block in many compressed data structures. Several recent applications need ...

    • Graph Compression for Adjacency-Matrix Multiplication 

      Francisco, Alexandre P.; Gagie, Travis; Köppl, Dominik; Ladra, Susana; Navarro, Gonzalo (Springer, 2022)
      [Abstract] Computing the product of the (binary) adjacency matrix of a large graph with a real-valued vector is an important operation that lies at the heart of various graph analysis tasks, such as computing PageRank. In ...

    • Improved Compressed String Dictionaries 

      Brisaboa, Nieves R.; Cerdeira-Pena, Ana; Bernardo, Guillermo de; Navarro, Gonzalo (ACM, 2019-11-03)
      [Abstract] We introduce a new family of compressed data structures to efficiently store and query large string dictionaries in main memory. Our main technique is a combination of hierarchical Front-coding with ideas from ...

    • Managing Compressed Structured Text 

      Brisaboa, Nieves R.; Cerdeira-Pena, Ana; Navarro, Gonzalo (Springer Nature, 2018-12-07)
      [Definition]: Compressing structured text is the problem of creating a reduced-space representation from which the original data can be re-created exactly. Compared to plain text compression, the goal is to take advantage ...

    • Navigating planar topologies in near-optimal space and time 

      Fuentes Sepúlveda, José; Navarro, Gonzalo; Seco, Diego (Elsevier B.V., 2023-02)
      [Abstract]: We show that any embedding of a planar graph can be encoded succinctly while efficiently answering a number of topological queries near-optimally. More precisely, we build on a succinct representation that ...

    • Optimizing RPQs over a compact graph representation 

      Arroyuelo, Diego; Gómez-Brandón, Adrián; Hogan, Aidan; Navarro, Gonzalo; Rojas-Ledesma, Javiel (Springer, 2023-09-07)
      [Absctract]: We propose techniques to evaluate regular path queries (RPQs) over labeled graphs (e.g., RDF). We apply a bit-parallel simulation of a Glushkov automaton representing the query over a ring: a compact ...

    • Space-efficient data structures for the inference of subsumption and disjointness relations 

      Fuentes Sepúlveda, José; Gatica, Diego; Navarro, Gonzalo; Rodríguez, M. Andrea; Seco, Diego (John Wiley and Sons Ltd, 2024)
      [Abstract]: Conventional database systems function as static data repositories, storing vast amounts of facts and offering efficient query processing capabilities. The sheer volume of data these systems store has a direct ...

    • Space/time-efficient RDF stores based on circular suffix sorting 

      Brisaboa, Nieves R.; Cerdeira-Pena, Ana; Bernardo, Guillermo de; Fariña, Antonio; Navarro, Gonzalo (Springer Nature, 2023-03)
      [Abstract]: The resource description framework (RDF) has gained popularity as a format for the standardized publication and exchange of information in the Web of Data. In this paper, we introduce RDFCSA, a compressed ...